Publisher Summary The constant terminal rate solution, which describes the pressure drop in the wellbore due to constant rate production, is the basic equation used in well test analysis. Apart from during the brief transient flow period, (infinite reservoir case) the solution depends critically on the reservoir boundary condition. In this chapter the constant terminal rate solution is presented for a well situated within a no-flow boundary for all the geometrical configurations considered by Matthews, Brons, and Hazebroek and for any value of the flowing time. The solutions are expressed in dimensionless form to simplify and generalize the mathematics. Superposition of such solutions leads to a general well test equation that can be applied to the analysis of any pressure test conducted in the wellbore. In this chapter such tests are described for reservoirs containing a fluid of small and constant compressibility (undersaturated oil).